1. Field of the Invention
The present invention relates to band saw machines and, more particularly, to band saw blade guides.
2. Brief Description of the Prior Art
As shown in FIG. 1, a band saw machine A typically includes a frame B, a first pulley C, a second pulley D vertically aligned with the first pulley C, a horizontal table E positioned between the two pulleys C, D and perpendicular to a portion of the frame B, a continuous band saw blade F with a serrated edge G tensioned around both pulleys C, D, and a motor P driving either one of the pulleys C, D. As the motor P rotates the first or second pulley C, D in a given direction, the band saw blade F and the non-driven pulley (C or D) rotate in the same direction as the driven pulley (C or D). The rotation of the band saw blade F causes a serrated edge G of the band saw blade F to form a cutting edge. This cutting edge is used to cut a workpiece, such as wood or other suitable materials.
A well-known problem with band saw machines A is blade F movement during cutting. Despite the tension exerted on the band saw blade F by the pulleys C, D, the blade F has a certain degree of lateral, rearward, and torsional movement about a fixed vertical axis V of the band saw blade F. The movement becomes more pronounced as a workpiece is brought in contact with the serrated edge G of the band saw blade F.
Band saw blade guides were developed to help limit movement of the blade during cutting and improve cutting precision. As shown in FIG. 1, band saw blade guides typically include a first thrust bearing H, a second thrust bearing I, a pair of first side guides J, Jxe2x80x2, and a pair of second side guides K, Kxe2x80x2. Both thrust bearings H, I are generally rotatable discs. The side guides J, Jxe2x80x2, K, Kxe2x80x2, such as those shown in more detail in FIG. 2, are generally adjustable blocks Q or rotatable discs. The first thrust bearing H is positioned perpendicular to a rear, non-cutting edge L of the band saw blade F, between the table E and the first pulley C. The second thrust bearing I is positioned perpendicular to the non-cutting edge L of the band saw blade F, between the table E and the second pulley D. Each pair of side guides J, Jxe2x80x2, K, Kxe2x80x2, is attached to the frame B or table E of the band saw machine A by a mounting bracket M. The blocks Q or discs are positioned opposite each side of the band saw blade F and parallel to one another, with one block on a first side N of the band saw blade F and one guide on a second side O of the band saw blade F. The first set of side guides J, Jxe2x80x2 is positioned between the first thrust bearing H and the table E, and the second set of side guides K, Kxe2x80x2 is positioned between the second thrust bearing I and the second pulley D. Both of the thrust bearings H, I and the side guides J, Jxe2x80x2, K, Kxe2x80x2 are adjustably spaced away from the non-cutting edge L, the first side N, and the second side O of the band saw blade F, and do not touch any portion of the band saw blade F until a workpiece is brought in contact with the band saw blade F.
In operation, a workpiece is brought in contact with the serrated edge G of the band saw blade F. As the workpiece is pressed against the rotating serrated edge G in a cutting position, the band saw blade F is pushed in a rearward direction Z (shown extending into the page in FIG. 1) with respect to the fixed vertical axis V of the band saw blade (also shown in FIG. 1). The first and second thrust bearings H, I contact the non-cutting edge L of the band saw blade F, stopping the rearward direction Z of the blade F. Similarly, the first and second side guides J, Jxe2x80x2, K, Kxe2x80x2 contact the first and second sides N, O of the band saw blade F when the band saw blade F is subjected to horizontal movement or torsional rotation about the fixed vertical axis V of the band saw blade F.
A disadvantage of the prior art is that a total of six band saw blade guides, including two thrust bearings H, I and two pairs of side guides J, Jxe2x80x2, K, Kxe2x80x2, are generally required to prevent excessive band saw blade F movement. Another disadvantage is that the prior art guides prevent the serrated edge G of the band saw blade F from pivoting about the non-cutting edge L of the band saw blade F. Pivotal movement is advantageous when making non-linear cuts in a workpiece. A further disadvantage of the prior art is that friction between the blocks Q in the side guides J, Jxe2x80x2, K, Kxe2x80x2 and the blade F creates heat which decreases the operating life of the band saw blade F.
To obviate the disadvantages of the prior art, the present invention includes a band saw blade guide for use with a band saw blade having a cutting edge and a non-cutting edge. The band saw blade guide includes a shaft having a first end and a second end. A wheel is carried on a first end of the shaft, and the wheel includes a circumferential groove. A base is connected to the second end of the shaft. The shaft is moveable along its longitudinal axis with respect to the base, the wheel is rotatably moveable with respect to the shaft, and the wheel is positioned to exert a continuous biasing force on the non-cutting edge of the band saw blade without imparting appreciable heat and friction on the rotating blade. The circumferential groove formed by the wheel, designed particularly for use with {fraction (1/16)}xe2x80x3 through xc2xcxe2x80x3 band saw blades, inhibits rearward, lateral, and torsional movement of the band saw blade while allowing the cutting edge of the band saw blade to pivot with respect to the non-cutting edge of the blade.
The band saw blade guide can be easily installed into a large variety of existing band saw blade machines, using existing prefabricated mounting cavities positioned adjacent the frame or mounting arms of the band saw machine. Moreover, the present invention eliminates two pairs of side guides and one thrust bearing.
In one method of guiding a band saw blade with a band saw blade guide, the band saw blade has a cutting edge and an opposite, non-cutting edge. The band saw blade guide includes a base and wheel which has a circumferential groove. The first preferred step is positioning the band saw blade guide adjacent the non-cutting edge of the band saw blade. The next step is aligning the circumferential groove in the wheel parallel to and centered on the non-cutting edge of the band saw blade. Once the groove is aligned, the next step is moving the wheel toward the non-cutting edge of the band saw blade, preferably by moving the base with respect to a mounting arm on the machine, until the non-cutting edge is seated within the groove of the wheel. Finally, the last step is moving the wheel a second time toward the non-cutting edge of the band saw blade, preferably xe2x85x9xe2x80x3, so that the non-cutting edge of the band saw blade is seated in the circumferential groove, is in constant contact with the non-cutting edge of the band saw blade, and exerts a constant biasing pressure on the non-cutting edge of the band saw blade.
In a second method, preferably used when there are first and second thrust bearings and first and second block guides installed on the band saw machine, the first step is to remove the existing first side guide before positioning a band saw blade guide according to the present invention adjacent the non-cutting edge of the band saw blade. The next step is opening the blocks on the existing second side guide so that they will not contact the band saw blade. Once the blocks are opened, the next step is pushing the first and second thrust bearings in a direction away from the non-cutting edge of the band saw blade, such as a rearward direction. The next step is installing the band saw blade guide in accordance with the first method, as discussed above. The last step is spacing the second thrust bearing away from the non-cutting edge of the band saw blade. The spacing is preferably 0.003xe2x80x3.
These and other advantages of the present invention will be clarified in the Detailed Description of the Preferred Embodiments taken together with the attached drawings in which like reference numerals represent like elements throughout.